This is a continuation of our work designed to provide a general method for use in radiation oncology. Its objectives are to improve tumor localization and three-dimensional definition both with respect to itself and surrounding normal tissues and then to provide treatment beam verification. In addition, the system will provide the data for direct input to the treatment planning computer. The system is based on the use of fluoroscopic video disc recorded images that can be used to produce transaxial tomograms upon which treatment beam profiles or port images may be superimposed. These images can be stored for the entire treatment period and may therefore be used to check the patient set-ups on a daily basis. The input screen is 17" x 17" and the video recordings are made using a low light level TV system. The input system can also serve in the same capacity as a conventional simulator. BIBLIOGRAPHIC REFERENCES: Baily, N.A., Lasser, E.C., and Keller, R.A., Tumor Localization and Beam Monitoring-Electro-fluorotomography. Medical Phys. 3, 176-180 (1976). Baily, N.A. and Nachazel, R.J., Analog Enhancement of Radiographic Images. Proc. of the San Diego Biomed. Symp., 15, 159-166 (1976).